SUMMARY ? MICROSCOPY AND TISSUE PROCESSING CORE The Microscopy and Tissue Processing Core provides the equipment, expertise, supplies and technical service to meet both the routine and advanced microscopy needs of NEI-funded investigators at UC Davis who emphasize cell biological approaches. Expensive devices such as cryostats, ultramicrotomes, ventilated embedding ovens, refrigerated UV polymerization units for catalyzing the polymerization of resins such as LR White, and freeze substitution systems, and hazardous reagents such as the heavy metal salts for EM and solvents and stains for LM, are all provided in a more cost-effective manner with a Core service. As many of these reagents and processes involve hazardous compounds, it is similarly more cost effective to have hazardous waste processing confined to a single unit. While most investigators are expert in the most sophisticated types of light microscopy, very few have the knowledge to conduct light and electron microscopy of embedded specimens. Having a single, well-trained staff person produces better results in a more efficient manner.